Theysohn and colleagues used functional MRI scans to capture brain activity while participants received electrical currents from a device attached to their ankles.

Functional MRI allows doctors to look at how blood flow increases in response to brain activity.

Participants were shocked until they yelled out, “Uncle, my pain is an eight,” on a 10-point scale, with 10 being the worst pain imaginable, Theysohn tells WebMD.

Then, acupuncture needles were placed at three places on the right side: between the toes, below the knee, and near the thumb. Participants were zapped until their pain was an eight again and a second set of MRI scans was taken.

Perception of Pain

At the annual meeting of the Radiological Society of North America here, Theysohn showed the two sets of scans.

Without acupuncture, there was a flurry of activity in some areas of the brain involved in pain perception. During acupuncture, activation in some of these pain-processing areas was reduced.

Acupuncture also affected brain activation in areas governing expectation of pain, similar to a placebo analgesic response, Theysohn says.

Asked why all the areas involved in pain were not activated when participants were shocked, Theysohn tells WebMD: "It's possibly due to the experimental setting. If we examined chronic back pain patients, this would be more complex and we would possibly have different results."

Other experts who heard the findings expressed cautious optimism.

"The relatively small study suggests acupuncture may have a role in controlling pain through a direct modulation of the brain's pain area," says Michael Brant-Zawadzki, MD, executive medical director of the Neurosciences Institute at Hoag Memorial Hospital in Newport Beach, Calif.

"That said, [functional MRI] is a bit of an expensive way to show that acupuncture can help people with pain. Simply asking patients if their pain was reduced or not could serve the same purpose," he tells WebMD.

On a research level, however, understanding the brain centers responsible for pain "may help us to develop new types of pain relievers" in the future, Brant-Zawadzki says.

This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.